Originally Posted by
moppeddler
I find this thread fascinating because I'm new to biking, and don't really know what any of it means. I looked up the specs on my bike (Trek 1.5) and it has a 12-30 Shimano Tiagra cassette. Does this mean there are 12 teeth on the lowest gear and 30 on the highest? Forgive my ignorance. My front sprocket (probably the wrong word) is a FSA Vero 50-34 compact. What does compact mean. Is this good or bad? Do these gears sound OK for doing hills? DO lower or higher numbers mean easire gears for climbing?
If someone could give me an overview of what all this means and what I should look for, it would be appreciated. Right now, I'm riding 1-2x/wk, usually 10-20 miles. So far avoiding big hills. Thanks in advance for any help.
The things that go into the gear ratio for a bike are the size of the front Chainring that you are using (you have a choice between 50 teeth and 34) and the size of the rear sproket (you have a variety of choices between 12 and 30). There are other things that go into the equation like the size of your wheels and length of the cranks, but for most bikes, those are essentially fixed, so they can be ignored.
The bigger the ratio between the front teeth and back teeth the faster the bike will go, and the harder it will be to pedal. For us old folks, when we are going up hills, most of us look for the smallest possible front chainring and combine that with the biggest rear sproket.
It is realtively easy to change the cassette in the rear to get a different range, or to change the front chainrings, but there are limits to both the min/max sizes and the ratios.
In the olden days, the cranks had a limit to the smaller size chainring on a double crank which was 39 teeth, so if you had a double, the smallest you could get would be 39, and you would want very strong legs to climb mountains with that. The other option was to get a triple chainring with a smaller third gear - or 'granny gear'. Today 'Compact Cranks' are popular where the bolt circle to attach the smaller ring on a double is smaller than the standard, and as a result you can get ratios like your 50-34.
Keep on peddling, and if you start hitting those hills and wishing you could go to a lower gear, you might consider using a cassette with bigger gears - which will make it easier, and slower.